Solvation consequences of polymer PVP with biological buffers MES,MOPS, and MOPSO in aqueous solutions

Densities and viscosities were measured for the aqueous buffer (MES, MOPS, or MOPSO) solutions containing different concentrations of polyvinylpyrrolidone (PVP) (5, 10, 15, 20 and 30) mass% at temperatures from (298.15 to 318.15) K under atmospheric pressure. The DFT calculations were also performed and the binding energies of the possible (PVP + buffer) complexes were obtained. The experimental and computational results reveal the interactions of the PVP with the constituent compounds in the aqueous buffer solutions. Additionally we have explored the solvation behavior of the buffers by measuring the densities and the viscosities data of the aqueous buffer solutions from (0.0 to 1.0) mol · kg⁻¹ at temperatures from (298.15 to 318.15) K. The viscosity results were correlated with the Jones–Dole equation. The correlated results confirmed that all the investigated buffers behave as Kosmotropes (structure makers).     

Effective chemical route for the synthesis of silver nanostructures in formamide

Poly(N-vinyl-2-pyrrolidone) (PVP) and gelatin protected silver nanostructures are prepared in formamide by simple chemical route. Both PVP and gelatin stabilized silver nanoparticles in formamide lead to the formation of nanostructures of various definite geometric shapes and sizes. The effect of anisotropy on the surface plasmon absorption band is analyzed by monitoring the UV-Visible absorption spectra of gelatin stabilized silver nanoparticles. The particles were characterized by UV-Visible absorption spectra and TEM.     

Na-MMT掺杂对PMA/PVP复合膜结构及光致变色性能的影响研究

将钠基膨润土(Na-MMT)掺入磷钼酸/聚乙烯基吡咯烷酮(PMA/PVP)体系中,利用透射电子显微镜(TEM)、原子力显微镜(AFM)、红外光谱(FTIR)、热重-差热(TG-DTA)、紫外-可见吸收光谱(UV-Vis)、X射线光电子能谱(XPS)等手段对复合薄膜的结构、热稳定性和光致变色性能进行了研究.红外光谱结果表明keggin结构磷钼酸和聚乙烯吡咯烷酮的基本结构在复合膜中仍然存在,复合膜中高分子与质子结合,以阳离子的形式与杂多阴离子成盐.Na-MMT的掺杂未对复合膜中PVP和PMA间的相互作用产生影响,但其掺杂提高了复合膜的热稳定性.在紫外光照下,复合膜由无色变为蓝色,杂多酸被还原产生杂多蓝.Na-MMT的掺杂降低了复合膜的光致变色响应性,这是由于多酸分子与钠基膨润土之间发生阳离子交换作用导致的.     

Novel Amphiphilic Poly(N-vinylpyrrolidone) Block Copolymer: Aggregative Behavior and Interaction with DNA

Summary: Novel block copolymers poly(N-vinylpyrrolidone)-block-poly[(tert-butoxy) carbonyl] tryptophanamido-N′-methacryl thiourea (PVP-b-PTAM-I, II and III) were synthesized by atom transfer radical polymerization (ATRP) in DMF using PVP-Cl as macroinitiator. The structures of the copolymers were characterized by UV-vis and GPC-MALLS. The results revealed that the copolymers with controlled molecular weight and relatively low polydispersity (PDI < 1.34) were obtained through ATRP. By means of dynamic light scattering (DLS) and transmission electron microscopy (TEM), we demonstrated that copolymer PVP-b-PTAM self-aggregated to form spherical micelles in aqueous solution and the size of the micelles increased with increasing hydrophobic contents. The interaction of PVP-b-PTAM with DNA was explored using ethidium bromide (EB) quenching experiments. The interaction between PVP-b-PTAM and DNA markedly depended on both the copolymer concentration and composition. The PVP-b-PTAM-II and III with higher hydrophobic contents exhibited highly complexed DNA ability at low copolymer concentration, such as 0.017 mg/mL, relative to PVP-b-PTAM-I. As the copolymer concentration further increased for PVP-b-PTAM-II and III, they first exhibited a sharply decreased affinity for DNA and then kept steady. The interaction mechanism between the amphiphilic copolymers and the EB-DNA complex was discussed in detail.     

基于PVP和PbSe三维自组装超晶格复合体系的电双稳器件

采用旋涂工艺将PbSe三维自组装超晶格镶嵌在两层聚合物PVP中,制备了基于PVP和PbSe三维自组装超晶格复合体系的电双稳器件,器件结构为ITO/PVP/PbSe三维自组装超晶格/PVP/Al,研究了其电学性能和记忆效应。与参比器件ITO/PVP/Al相比,器件ITO/PVP/PbSe三维自组装超晶格/PVP/Al的电流-电压特性呈现出非常明显的电双稳特性和非易失记忆行为,在相同的电压下同时具有两种不同的导电状态：低电导的关态和高电导的开态。当PVP与PbSe超晶格的质量比为1：1时,器件性能最好,其最大电流开关比为7×10⁴,经过10⁴ s仍几乎无衰减。通过对电流-电压曲线拟合,利用不同的导电模型对器件的载流子传输机制进行了解释。结果表明,PbSe三维自组装超晶格作为电荷陷阱,可以俘获、储存及释放电荷,对器件的电双稳性能能起决定性作用。     

以PVP纳米纤维为模板采用原子层沉积法制备MgxZn1-xO纳米纤维及其光学性质研究

采用静电纺丝方法制备聚乙烯吡咯烷酮(PVP)纳米纤维,并以其为模板采用原子层沉积(ALD)方法制备不同Mg掺杂浓度的MgxZn1-xO纳米纤维。研究了不同Mg掺杂浓度对复合纳米纤维结构和光学性质的影响。利用场发射扫描电子显微镜(FESEM)、光致发光(PL)和紫外-可见光(UV-Vis)吸收谱对样品测试并进行表征分析。结果表明,Mg元素的掺入并没有改变ZnO纳米纤维的形貌,所有样品的表面形貌极其相似,只是掺杂后纤维直径有所增大;随着Mg掺杂浓度的增加吸收边逐渐发生蓝移,表明所制备MgxZn1-xO纤维的带隙具有可调节性。与此同时,在PL谱中可以观察到样品的紫外(UV)发光峰从377nm移动至362nm,且与不掺杂的样品相比,MgxZn1-xO纳米纤维的UV发光强度明显增强。通过这种方法可以合成组分可控的MgxZn1-xO纳米纤维。在ZnO中掺入Mg元素可以有效地提高ZnO-PVP纳米纤维的禁带宽度以及UV发射强度。     

ZnS：Mn/SiO2量子点的表面聚乙烯吡咯烷酮修饰及其应用于海水中铅离子检测

制备了二氧化硅壳层修饰的ZnS：Mn量子点,基于聚乙烯吡咯烷酮（PVP）与二氧化硅表面硅羟基的作用,在纳米复合微粒表面进行了PVP的修饰,得到了在海水中荧光性能及胶体稳定性良好的ZnS：Mn/SiO₂/PVP 量子点。在Pb²⁺对所制备纳米微粒具有荧光猝灭效应的基础上,建立了用ZnS：Mn/SiO₂/PVP 量子点作为荧光探针检测海水中微量铅离子的新方法。研究表明,量子点浓度为10^-3 mol/L时,海水中离子浓度在10~100 μmol/L范围内与ZnS：Mn/SiO₂/PVP量子点荧光猝灭强度呈良好的线性关系,相关系数为0.994 6,检出限为8×10^-7 mol/L。     

静电纺丝制备Eu(BA)3phen/PANI/PVP光电双功能复合纳米纤维及其性能

采用静电纺丝技术将聚苯胺(PANI)和稀土配合物Eu(BA)3phen掺杂到高分子材料聚乙烯吡咯烷酮(PVP)中, 制备出新型的具有光电双功能的Eu(BA)3phen/PANI/PVP复合纳米纤维. 采用扫描电子显微镜、 X射线能量色散谱仪、 荧光光谱仪及宽频介电松弛谱仪对样品进行了表征. 实验结果表明, 复合纳米纤维直径为(270±31) nm. 在275 nm紫外光激发下, Eu(BA)3phen/PANI/PVP复合纳米纤维发射出主峰位于580, 594和617 nm的红光, 对应于Eu3+的 5D0→7F0, 5D0→7F1和5D0→7F2跃迁. 当m[Eu(BA)3phen]:m(PANI):m(PVP)=15:10:100 时, 复合纳米纤维的荧光发射最强. 复合纤维的电导率随PANI含量的增大而升高. 在m(PANI):m(PVP)=50:100时, 其电导率在高频(106 Hz)下达到1.5×10-6 S/cm.     

含铕配合物荧光纳米纤维的制备及光学性质的研究

通过静电纺丝技术,将发光良好的稀土配合物Eu(DBM)₃·H₂O和Eu(DBM)₄·CPC纳米微粒复合到水溶性的聚乙烯基吡咯烷酮中,制备了具有稀土铕离子红色特性荧光的聚合物纳米纤维。通过对稀土配合物以及聚合物纳米纤维样品扫描电镜和透射电镜的测试,发现当稀土配合物复合到聚合物纳米纤维中后,由于与聚乙烯基吡咯烷酮乙醇溶解性良好,其微观结构发生了变化,得到了50～100 nm左右的比较均匀的线状结构。同时,通过对稀土配合物以及聚合物纳米纤维样品的荧光激发、发射光谱及荧光寿命进行研究,表明稀土配合物在聚合物纳米纤维中比其在粉末状有更高的发光强度及更长的荧光寿命,其原因在于高分子纳米纤维为稀土配合物提供了较稳定的化学环境。     

PVP/Pd/IrO_2/Nafion修饰微电极用于成纤维细胞中一氧化氮释放的研究

采用PVP/Pd/IrO_2/Nafion修饰电极对成纤维细胞中NO的释放情况进行了研究 。结果表明,在正常状态下,采用NO前体L-精氨酸和乙酰胆碱对成纤维细胞进行刺 激后没有NO的释放;当用脂多糖进行诱导后,则释放出高浓度的NO,加入L-精氨酸 和乙酰胆碱都促进了NO的合成,而L-NNA的加入则逆转了L-精氨酸和乙酰胆碱的作 用。